1. Field of the Invention
The present invention relates generally to a nuclear liquid waste tank and, more particularly, to a system for removing liquid waste from such a waste tank.
2. Description of the Prior Art
A typical nuclear power facility includes a nuclear reactor wherein a controlled nuclear reaction, which generates heat, is occurring. Typically, borated water is contained in the reactor for controlling the nuclear reaction process and for passing the heat away from the reactor. A primary loop communicating with the reactor functions to pass the borated water (i.e., the heat) away from the reactor and to transfer the heat to a secondary loop. The secondary loop is isolated from the primary loop and generates steam from the heat passed from the primary loop. The steam of the secondary loop is used to produce electricity as is well known in the art. The primary loop then returns the borated water back into the reactor where the above described process is repeated.
It may become necessary during normal operation, maintenance purposes, or the like to withdraw or insert borated water into the primary loop. In this regard, two pipes are attached to the primary loop; one for adding additional borated water and the other for withdrawing borated water. The withdrawn borated water (i.e., liquid waste) is passed to a series of waste tanks where the borated water is processed in each tank before being released to the environment.
These liquids which are exposed to radiation (i.e, the liquid waste) must be properly treated before being introduced to the environment. A portion of this treatment typically occurs in cylindrical waste tanks.
The waste tanks each have a cylindrical shaped housing enclosed on both its ends by circular shaped ends. Each tank is laid over on its side, and an outlet is attached to the lower portion of one end for selectively releasing the liquid waste inside. A pump is attached atop the housing, and a pipe extends between the pump and the outlet. The pump functions to suction the liquid waste out of the tanks. The liquid waste, after being properly mixed, sampled, and treated within the tank, may either be released for further processing if it is not the final tank in the series or released to the environment if it is the final tank in the series.
Although the present system for withdrawing the liquid waste from the tanks is satisfactory, it is not without drawbacks. Dust and the like may settle in the tank interior adjacent to the outlet and, therefore, clog the outlet which prevents drainage. Further, incomplete drainage may occur because the outlet, although near the end lower portion, will not completely drain the liquid waste below the outlet. Still further, mixing the contents of the tank and cleaning the tank requires additional devices which are not part of the tank.
Consequently, a need exists for improvements in the construction of nuclear tanks containing liquid waste to facilitate drainage.